A Parallel Programming Primer. by Alan G. Labouseur

Transcription

1 Parallel Programming Primer by lan G. Labouseur

2 Parallel Programming Primer by lan G. Labouseur

3 Parallel Programming Primer by lan G. Labouseur

4 Parallel Programming Primer by lan G. Labouseur Mission Brief: 1.History 2.ata Parallel 3.ask Parallel 4.Yesterday 5.oday 6.omorrow

5 History Early Parallel Programming

6 ata Parallel 1984 ewitt s Gamma atabase Machine Many processors, many disks Sharednothing architecture hree keys to parallelism: 1. Coordinated scheduling 2. Parallel hash algorithms for relational operators 3. ables are horizontally partitioned/declustered hree declustering strategies

7 ata Heap Node Node 1 Node 2 03 ata Parallel RoundRobin eclustering

8 ata Heap Node 1 Node 2 Node ata Parallel RoundRobin eclustering

9 ata Heap Node 0 02 Node 2 (Goofy) Hash function: Even or Odd Node 1 01 ata Parallel Hashed eclustering

10 ata Heap Node 1 Node 2 Node 0 (Goofy) Hash function: Even or Odd ata Parallel Hashed eclustering

11 ata Heap Node 1 Node 2 Node Range able Condition Node id <= 5 0 id > 5 and id <= 10 1 id > ata Parallel Sharded eclustering

12 We re done, right? NO! istributing the data is only half the battle. Bad News: Moore s Law is leveling out. CPU cores aren t getting much faster. hus limiting our capabilities on a singlecpu Good News: We re getting more cores every day. Intel i7 Ivy Bridge microprocessor dualcore (2 real / 4 virtual) quadcore (4 real / 8 virtual)

13 ask (Function) Parallel Singlecore Quadcore ll we need is programming language support.

14 Family History LGOL 1960s Pascal, C 1970s C s Java, elphi 1990s C# 2000s

15 Family History LGOL 1960s Pascal, C 1970s C s Java, elphi 1990s C# 2000s

16 Yesterday C++ / Java / C# Sharedstate concurrency Encapsulation is not complete hread scheduling does not obey encapsulation rules regardless of how you write your objects. Most code is unsafe for scaling up or out.

17 Yesterday C++ / Java / C# Concurrency is in the plumbing evelopers are responsible for determinism... by adding locks, semaphores, monitors, which cause race conditions and deadlock. BNG HE HERE hread safety a programmer problem.

18 Yesterday C++ / Java / C# Refactoring is complicated and error- prone. Needs IE to help out Mutable State Side effects Heisenbugs ifbicult to parallelize.

19 nother Family History LGOL 1960s LISP Pascal, C 1970s ML C s Erlang Java, elphi 1990s Haskell C# 2000s F#, Scala

20 nother Family History LGOL 1960s LISP Pascal, C 1970s ML C s Erlang Java, elphi 1990s Haskell C# 2000s F#, Scala

21 oday C++ / Java / C# Erlang / Scala Sharedstate concurrency Encapsulation is not complete hread scheduling does not obey encapsulation rules regardless of how you write your objects. X Sharednothing concurrency Encapsulation of state and behavior is complete ctors are completely isolated, only communicating with messages. Most code is unsafe for scaling up or out. Most code is safe for scaling up and out.

22 oday C++ / Java / C# Erlang / Scala X Concurrency is in the plumbing evelopers are responsible for determinism... by adding locks, semaphores, monitors, which cause race conditions and deadlock. hread safety a programmer problem. ctors hoist the concurrency abstraction from the plumbing to the workblow. evelopers are responsible workblow... by passing immutable messages to non- blocking asynchronous actors. hread safety is a runtime feature.

23 oday C++ / Java / C# Erlang / Scala Refactoring is complicated and error- prone. Needs IE to help out Mutable State Side effects X ype inference makes much refactoring instant and errorfree. No IE help, it s in the language Immutable State - No side effects Heisenbugs Fewer bugs ifbicult to parallelize. Easier to parallelize (within the limits noted by mdahl and Gustafson).

24 oday Erlang in the world mazon, Facebook, British elecom, Mobile, Xerox, Jane Street, Google, pple, Basho, Ericsson, Heroku, InfoQ, and many others, especially in Europe. Scala in the world witter, LinkedIn, FourSquare, Siemens, Sony Pictures, umblr, UBS, Morgan Stanley, Capital IQ, Google, HP, ebay, zeebox, Heroku, and many more.

25 omorrow Go out and learn Erlang. Go out and learn Scala.